From the Barral's Institute website:

Barral's clinical work with the viscera led to his development of a form of manual therapy that focuses on the internal organs, their environment, and the potential influence on many structural and physiological dysfunctions. The term he coined for this therapy was Visceral Manipulation (VM). The purpose of VM is to re-create, harmonize, and increase proprioceptive communication in the body to enhance its internal mechanism for better health, thereby revitalizing a person, and relieving symptoms of pain, dysfunction, and poor posture. Visceral Manipulation treats a person's functional and structural imbalances with an aim to affect their musculoskeletal, vascular, nervous, urogenital, respiratory, digestive, and lymphatic dysfunction.

Jean-Pierre Barral's famous dictum, “Only the tissues know,” expresses that the tissues in the body have a deep and innate intelligence. Everything that has happened in our lives—injuries, diseases, stressors, etc.—is recorded in our tissues. At the core of Visceral Manipulation (VM) is 'listening' to the tissues with our hands. Through manual listening techniques, trained hands of a skilled practitioner feel where the tissues are pulling toward the areas of restriction, the areas where the body is not moving, and the areas of the greatest impact on the person's well-being from the manual therapy perspective.

Comparative studies found Visceral Manipulation beneficial for people with various conditions such as:

Source: https://www.barralinstitute.com/therapies/